Wiring substrate, semiconductor package having the wiring substrate, and manufacturing method thereof

ABSTRACT

Provided is a wiring substrate and its manufacturing method in which a thick wiring layer capable of being applied with a large current and a thin wiring layer capable of being subjected to microfabrication coexist in the same layer. The wiring substrate includes: an insulating film located over a first wiring and having a via; and a second wiring over the insulating film. The second wiring has a stacked structure including a first layer and a second layer covering the first layer. The second layer is in direct contact with the first wiring in the via. A thickness of the second layer in a region overlapping with the first layer is different from a thickness of the second layer in the via.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority from theprior Japanese Patent Application No. 2015-241907, filed on Dec. 11,2015, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a wiring substrate, a semiconductorpackage or a stacked-type semiconductor package having the wiringsubstrate, and a manufacturing method thereof. For example, the presentinvention relates to a wiring substrate for a power device which isdriven with a large current, a semiconductor package or a stacked-typesemiconductor package having the wiring substrate, and a manufacturingmethod thereof.

BACKGROUND

A power semiconductor device is a semiconductor device having a basicfunction of converting and controlling electric power. A powersemiconductor device plays an important role not only in an applicationto an inverter and a small-sized motor employed in consumer electronicsand electronic office equipment but also in management of conversion andcontrol of electric power of an electronic power system in a power plantand a motor-driving system in a train, a vehicle, and so on. Apart froma semiconductor device such as a thin-film transistor utilized in adisplay device, a power device is driven at a large voltage and appliedwith a large current. Therefore, as disclosed in Japanese patentapplication publications No. 2013-219267, 2005-79462, and 2015-162516, ameasure against heat generation from wiring due to a large current hasbeen investigated.

SUMMARY

An embodiment of the present invention is a wiring substrate including:an insulating film located over a first wiring and having a via; and asecond wiring over the insulating film. The second wiring has a stackedstructure including a first layer and a second layer covering the firstlayer. The second layer is in direct contact with the first wiring inthe via. A thickness of the second layer in a region overlapping withthe first layer is different from a thickness of the second layer in thevia.

In the embodiment, the thickness of the second layer in the via may belarger than the thickness of the second layer in the region overlappingwith the first layer. A thickness of the first layer may be larger thanthe thickness of the second layer in the region overlapping with thefirst layer. The first layer and the second layer may include copper.The first layer and the second layer may be different in conductivityfrom each other. A top surface of the insulating film may have adepression between the via and the first layer.

An embodiment of the present invention is a wiring substrate including:an insulating film located over a first wiring and having a via; and asecond wiring over the insulating film. The second wiring has a stackedstructure including: a second layer in direct contact with the firstwiring in the via; and a first layer over and electrically connected tothe second layer. A thickness of the second layer in a regionoverlapping with the insulating film is different from a thickness ofthe first layer in the via.

In the embodiment, a thickness of the second layer in the via may belarger than the thickness of the second layer in the region overlappingwith the insulating film. A thickness of the first layer may be largerthan the thickness of the second layer in the region overlapping withthe insulating film. The first layer and the second layer may includecopper. The first layer and the second layer may be different inconductivity from each other.

An embodiment of the present invention is a semiconductor packageincluding: a semiconductor device having a terminal; an insulating filmlocated over the terminal and having a via; and a wiring over theinsulating film. The wiring has a stacked structure including a firstlayer and a second layer covering the first layer. The second layer isin direct contact with the terminal in the via, and a thickness of thesecond layer in a region overlapping with the first layer is differentfrom a thickness of the second layer in the via.

In the embodiment, the thickness of the second layer in the via may belarger than the thickness of the second layer in the region overlappingwith the first layer. A thickness of the first layer may be larger thanthe thickness of the second layer in the region overlapping with thefirst layer. The first layer and the second layer may include copper.The first layer and the second layer may be different in conductivityfrom each other. A top surface of the insulating film may have adepression between the via and the first layer.

An embodiment of the present invention is a semiconductor packageincluding: a semiconductor device located over a first wiring and havinga first terminal and a second terminal; an insulating film located overthe second terminal and having a via; and a second wiring over theinsulating film. The second wiring has a stacked structure including: asecond layer in direct contact with the second terminal in the via; anda first layer located over and electrically connected to the secondlayer. A thickness of the second layer in a region overlapping with theinsulating film is different from a thickness of the second layer in thevia.

In the embodiment, the thickness of the second layer in the via may belarger than the thickness of the second layer in the region overlappingwith the insulating film. A thickness of the first layer may be largerthan the thickness of the second layer in the region overlapping withthe insulating film. The first layer and the second layer may includecopper. The first layer and the second layer may be different inconductivity from each other.

An embodiment of the present invention is a manufacturing method of awiring substrate. The manufacturing method includes: forming aninsulating film over a first wiring; and forming, over the insulatingfilm, a second wiring having a first layer and a second layer. Theformation of the second wiring includes: forming the second layer bybonding a metal plate to the insulating film; exposing the insulatingfilm by forming an opening portion in the second layer; exposing thefirst wiring by forming a via in the insulating film; and forming thefirst layer with an electroplating method so that the first layer islocated over and in direct contact with the first wiring and the secondlayer.

In the embodiment, a thickness of the second layer in the via may belarger than a thickness of the second layer in a region overlapping withthe first layer. A thickness of the first layer may be larger than thethickness of the second layer in the region overlapping with the firstlayer. The first layer and the second layer may include copper. Thefirst layer and the second layer may be different in conductivity fromeach other.

An embodiment of the present invention is a manufacturing method of awiring substrate. The manufacturing method includes: forming aninsulating film over a first wiring; exposing the first wiring byforming a via in the insulating film; and forming, over the insulatingfilm, a second wiring having a first layer and a second layer. Theformation of the second wiring includes: forming the second layer withan electroplating method so that the second layer is located over and incontact with the first wiring and the insulating film; and forming thefirst layer by disposing a metal plate over the second layer so that thefirst layer is electrically connected to the second layer.

In the embodiment, a thickness of the second layer in the via may belarger than a thickness of the second layer in a region overlapping withthe insulating film. A thickness of the first layer may be larger thanthe thickness of the second layer in the region overlapping with theinsulating film. The first layer and the second layer may includecopper. The first layer and the second layer may be different inconductivity from each other.

An embodiment of the present invention is a manufacturing method of asemiconductor package. The manufacturing method includes: forming asemiconductor device over a first wiring, the semiconductor devicehaving a first terminal and a second terminal; forming an insulatingfilm over the second terminal; and forming, over the insulating film, asecond wiring including a first layer and a second layer. The formationof the second wiring includes: forming the second layer by bonding ametal plate to the insulating film; exposing the insulating film byforming an opening portion in the second layer; exposing the firstwiring by forming a via in the insulating film; and forming the firstlayer with an electroplating method so that the first layer is locatedover and in direct contact with the first wiring and the second layer.

In the embodiment, a thickness of the second layer in the via may belarger than a thickness of the second layer in a region overlapping withthe first layer. A thickness of the first layer may be larger than thethickness of the second layer in the region overlapping with the firstlayer. The first layer and the second layer may include copper. Thefirst layer and the second layer may be different in conductivity fromeach other. A top surface of the insulating film may have a depressionbetween the via and the first layer.

An embodiment of the present invention is a manufacturing method of asemiconductor package. The manufacturing method includes: forming asemiconductor device over the first wiring, the semiconductor devicehaving a first terminal and a second terminal; forming an insulatingfilm over the second terminal; and forming, over the insulating film, asecond wiring including a first layer and a second layer. The formationof the second wiring includes: forming the second layer with anelectroplating method so that the second layer is located over and incontact with the first wiring and the insulating film; and forming thefirst layer by disposing a metal plate over the second layer so that thefirst layer is electrically connected to the second layer.

In the embodiment, a thickness of the second layer in the via may belarger than a thickness of the second layer in a region overlapping withthe insulating film. A thickness of the first layer may be larger thanthe thickness of the second layer in the region overlapping with theinsulating film. The first layer and the second layer may includecopper. The first layer and the second layer may be different inconductivity from each other.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A to FIG. 1E are drawings showing a wiring substrate and itsmanufacturing method of an embodiment of the present invention;

FIG. 2A to FIG. 2D are drawings showing a wiring substrate and itsmanufacturing method of an embodiment of the present invention;

FIG. 3A to FIG. 3D are drawings showing a wiring substrate and itsmanufacturing method of an embodiment of the present invention;

FIG. 4A and FIG. 4B are drawings showing a wiring substrate and itsmanufacturing method of an embodiment of the present invention;

FIG. 5A to FIG. 5C are drawings showing a semiconductor package and itsmanufacturing method of an embodiment of the present invention;

FIG. 6A to FIG. 6C are drawings showing a semiconductor package and itsmanufacturing method of an embodiment of the present invention;

FIG. 7A to FIG. 7C are drawings showing a semiconductor package and itsmanufacturing method of an embodiment of the present invention;

FIG. 8A to FIG. 8C are drawings showing a semiconductor package and itsmanufacturing method of an embodiment of the present invention;

FIG. 9A and FIG. 9B are drawings showing a semiconductor package and itsmanufacturing method of an embodiment of the present invention;

FIG. 10A and FIG. 10B are drawings showing a semiconductor package andits manufacturing method of an embodiment of the present invention;

FIG. 11 is a circuit diagram of a semiconductor package of an embodimentof the present invention;

FIG. 12 is a cross-sectional view of a semiconductor package of anembodiment of the present invention; and

FIG. 13 is a cross-sectional view of a semiconductor package of anembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the embodiments of the present invention are explained withreference to the drawings. Note that the present invention can beimplemented in a variety of modes within the concept of the invention,and the interpretation should not be limited by the disclosure in theembodiments represented below.

In the drawings, the width, thickness, shape, and the like of eachcomponent may be schematically illustrated and different from those ofan actual mode in order to provide a clearer explanation. However, thedrawings simply give an example and do not limit the interpretation ofthe present invention. In the specification and each of the drawings,elements which are the same as those explained in the preceding drawingsare denoted with the same reference numbers, and their detailedexplanation may be omitted appropriately.

It is properly understood that another effect different from thatprovided by the modes of the embodiments described below is achieved bythe present invention if the effect is obvious from the description inthe specification or readily conceived by persons ordinarily skilled inthe art.

First Embodiment

In the present embodiment, a wiring structure used in a wiring substrateof an embodiment of the present invention and its manufacturing methodare explained with reference to FIG. 1A to FIG. 1E. As shown in FIG. 1E,this wiring structure has a wiring (second wiring 140) in which a layer(first layer 125) having a large thickness and capable of being appliedwith a large current and a layer (second layer 130) having a smallthickness and capable of being subjected to microfabrication are stackedand electrically connected to each other. Furthermore, the second layer130 with a small thickness is also formed in a via. Such a wiringstructure can be utilized to establish an electrical connection instacked wiring layers and wiring substrates.

Specifically, as shown in FIG. 1A, an insulating film 110 is formed overa first wiring 100. The first wiring 100 may be a wiring formed over aninsulating substrate such as a glass or plastic substrate or anextraction wiring or a pad mounted on an IC chip or a power device. Thefirst wiring 100 can include a metal such as gold, copper, titanium,molybdenum, and aluminum. An organic material such as an acrylic resin,a polyimide resin, a polyester resin can be used for the insulating film110, and the insulating film 110 can be formed with a wet-typefilm-formation method such as a spin-coating method, an ink-jet method,and a printing method. Alternatively, the insulating film 110 may beformed by disposing a film of the aforementioned resin over the firstwiring 100 and then pressing the film (lamination processing).

Next, a metal plate 120 is bonded to the insulating film 110 (FIG. 1Aand FIG. 1B). Copper, gold, and the like can be used for the metal plate120, for example. A thickness of this metal plate 120 can be selectedfrom a thickness which allows a current required by the wiring substrateto flow sufficiently. For example, the thickness can be selected from 1μm to 10 mm and is preferably 100 μm to 300 μm. The metal plate 120 maybe bonded by applying pressure from over the insulating film 110 whileheating. In FIG. 1A, the metal plate 120 has a depression formed by halfetching or the like. The formation of the depression facilitates theformation of an opening portion described below. However, the embodimentis not limited to such a mode, and the metal plate 120 which does notcontain the depression and has a flat surface as a whole may beemployed.

Next, as shown in FIG. 10, the opening is formed in the metal plate 120with a method such as etching to expose the insulating film 110, and afirst layer 125 is simultaneously formed. When the metal plate 120 hasthe depression, the opening can be readily constructed at a positioncorresponding to the depression by conducting the etching in a regionoverlapping with the depression (from a side opposite to thedepression). The etching may be any method of dry etching and wetetching.

Next, as shown in FIG. 1D, the via 115 is formed by performing laserprocessing or etching on the insulating film 110 which is exposed byforming the opening portion in the metal plate 120. With this process, asurface of the first wiring 100 is exposed.

After that, as shown in FIG. 1E, the second layer 130 is formed with anelectroplating method and the like. As an electroplating method, acopper-electroplating method, a gold-electroplating method, or the likemay be employed, by which the second layer 130 including copper or goldis formed. The wiring having the structure in which the first layer 125and the second layer 130 are stacked is the second wiring 140.

At this time, the second layer 130 is formed so as to cover the firstlayer 125 and fill the via 115. In other words, a thickness of thesecond layer 130 in a region overlapping with the first layer 125 isdifferent from a thickness of the second layer 130 in the via 115, andthe latter is larger. Note that, when the thickness of the second layer130 formed in the via 115 is small, the via 115 may be filled with aconductive paste and the like after or before the formation of thesecond layer 130, for example. As a conductive paste, a gold paste, asilver paste, and the like can be used. After that, a circuit wiring maybe formed by processing the second layer 130 with a method such asetching, if necessary.

The thickness of the second layer 130 can be smaller than a thickness ofthe first layer 125. Specifically, the thickness of the second layer 130in the region overlapping with the first layer 125 is smaller than thethickness of the first layer 125. Therefore, the formation time of thesecond layer 130 can be reduced, and the process can be shortened. Thethickness of the second layer 130 can be 1 μm to 50 μm or preferably 10μm to 30 μm.

The first layer 125 and the second layer 130 may be different inelectrical resistivity. Alternatively, they may be different in impurityconcentration. Alternatively, they may be different in density.

Note that the second layer 130 can be formed by a sputtering method andthe like in addition to an electroplating method.

Generally, when a power device is packaged, a wire bonding and a methodusing a clip electrode are employed for the connection of a power deviceto an external electrode. Apart from a semiconductor device such as athin-film transistor utilized in a display, a power device is driven ata high voltage and is applied with a large current. The difficulty of aconnection method such as the wire bonding in increasing a thickness ofwiring causes a problem of heat generation resulting from a wiringresistance when applied with such a large current.

Additionally, a stacked-type package having a structure in which thewhole of the chip is embedded in an insulating resin and wiring layersand insulating layers are stacked into a layered structure has beenproposed in order to satisfy the recent requirement such as highintegration, cost reduction, and miniaturization of devices. In such astacked-type package, a via wiring is used to achieve an electricalconnection between different layers, a via is filled and a wiring layeris formed simultaneously with an electroplating method and the like.However, the electroplating method is not suitable for the formation ofa wiring having a large thickness, and the formation of a thick wiringlayer requires an extremely long time, which leads to a decrease inmanufacturing efficiency and an increase in manufacturing cost.

Moreover, a thick wiring layer is necessary to suppress heat generationfrom a wiring because a large current is applied to a power device asdescribed above. Hence, the use of a via wiring formed with anelectroplating method and having a relatively small thickness leads to aserious problem of heat generation due to the wiring resistance. On theother hand, when a wiring having a large thickness is formed by using ametal plate and the like, heat generation can be suppressed. However,this method cannot fill a via. Furthermore, it is difficult to performmicrofabrication on a wiring having a large thickness, and a wiringstructure having a high degree of integration cannot be fabricated. Forexample, in a module package in which a power device, a control IC, andthe like coexist, the smallest design rule in the formation of a thickmetal wiring for a power device is larger than a space betweenelectrodes of a control IC. A power device and a control IC cannot besimultaneously patterned by using the same wiring because it isnecessary to arrange a wiring in a higher degree of integration in awiring of a control IC.

However, in the wiring structure according to the present embodiment, ametal layer (the first layer 125 in the present embodiment) formed byusing a metal plate and having a large thickness and a metal layer (thesecond layer 130 in the present embodiment) formed with anelectroplating method and the like and having a small thickness arehybridized. Hence, a large current can be applied by using the firstlayer 125 as a main conduction route, which allows the operation of apower device. On the other hand, the second layer 130 formed with anelectroplating method and the like can be utilized in a region in whicha large current does not flow but a wiring arrangement in a high degreeof integration is required. Therefore, a wiring patterning for a controlIC is feasible. With this structure, devices such as a power device anda control IC, which require different design rules, can be arranged inthe same layer and can be connected in the same wiring process.

Second Embodiment

In the present embodiment, a wiring structure of a wiring substratedifferent from that of the First Embodiment is described by using FIG.2A to FIG. 2D. Description of the structures which are the same as thoseof the First Embodiment may be omitted.

As shown in FIG. 2D, the wiring structure used in the wiring substrateof an embodiment of the present invention has a wiring (second wiring240) in which a layer (first layer 230) having a large thickness andcapable of being applied with a large current and a layer (second layer220) having a small thickness and capable of being subjected tomicrofabrication are stacked and electrically connected to each other.Furthermore, the second layer 220 with a small thickness is also formedin a via. Similar to the First Embodiment, such a wiring structure canbe utilized to establish an electrical connection in stacked wiringlayers and wiring substrates.

First, an insulating film 210 is formed over a first wiring 200, and theinsulating film 210 is processed to form the via 215 (FIG. 2A and FIG.2B). For a material and a film-formation method usable for theinsulating film 210, those described in the First Embodiment can beapplied.

After that, the second layer 220 is formed over the insulating film 210with an electroplating method, a sputtering method, and the like (FIG.2C). As an electroplating method, the method described in the FirstEmbodiment can be applied. At this time, the second layer 220 is formedso as to fill the via 215. In other words, a thickness of the secondlayer 220 in a region overlapping with the insulating film 210 isdifferent from a thickness of the second layer 220 in the via 215, andthe latter is larger. Note that, similar to the First Embodiment, whenthe thickness of the second layer 220 formed in the via 215 is small,the via 215 may be filled with a conductive paste and the like after orbefore the formation of the second layer 220, for example. The specificthickness of the second layer 220 is the same as that of the FirstEmbodiment.

Next, as shown in FIG. 2D, a metal plate is bonded over the second layer220 with a metal bonding layer 225 interposed therebetween to form thefirst layer 230. Copper, gold, and the like can be used for the metalplate 120, for example. A thickness of this metal plate can be selectedfrom a thickness which allows a current required by the wiring substrateto flow sufficiently and can be selected from the thicknesses describedin the First Embodiment. The metal plate may be bonded by applying apressure from over the metal bonding layer 225 while heating. For themetal bonding layer 225, a metal having a relatively low melting point,such as zinc and tin, or its alloy can be used, and the metal mayfurther include phosphorous at several percent (e.g., 3% to 10% or 5% to8%). After that, the first layer 230 may be processed into a requiredshape by using an etching method and the like. The wiring having thestructure in which the first layer 230 and the second layer 220 arestacked is the second wiring 240.

A thickness of the second layer 220 may be smaller than a thickness ofthe first layer 230. Specifically, the thickness of the second layer 220in a region overlapping with the insulating film 210 is smaller than thethickness of the first layer 230. Therefore, the formation time of thesecond layer 220 can be reduced, and the process can be shortened.

The second layer 220 and the first layer 230 may be different inelectrical resistivity. Alternatively, they may be different in impurityconcentration. Alternatively, they may be different in density.

As described in the First Embodiment, in the wiring structure in thepresent embodiment, a metal layer (the first layer 230 in the presentembodiment) formed with a metal plate and having a large thickness and ametal layer (the second layer 220 in the present embodiment) formed withan electroplating method and the like and having a small thickness arehybridized. Hence, a large current can be applied by using the firstlayer 230 as a main conduction route, which allows the operation of apower device. On the other hand, the second layer 220 formed with anelectroplating method and the like can be utilized in a region in whicha large current does not flow but a wiring arrangement in a high degreeof integration is required. Therefore, wiring patterning for a controlIC is feasible. With this structure, devices such as a power device anda control IC, which require different design rules, can be arranged inthe same layer and can be connected in the same wiring process.

Third Embodiment

In the present embodiment, a wiring structure of a wiring substratedifferent from those of the First and Second Embodiments is described byusing FIG. 3A to FIG. 4B. Description of the structures which are thesame as those of the First and Second Embodiments may be omitted.

The wiring structure of the wiring substrate of the present embodimentis different from that of the First Embodiment in that an insulatingfilm 310 formed over a first wiring 300 has a depression as shown inFIG. 4B.

First, as shown in FIG. 3A, the insulating film 310 is formed over thefirst wiring 300. For a material and a film-formation method usable forthe first wiring 300 and the insulating film 310, those described in theFirst Embodiment can be used.

Next, a metal plate 320 is bonded to the insulating film 310 (FIG. 3Aand FIG. 3B). A material and a thickness of the metal plate 320 can beselected from the ranges described in the First Embodiment. Moreover, asa bonding method of the metal plate 320, the method described in theFirst Embodiment can be employed. In FIG. 3A, the metal plate 320 has aplurality of depressions formed by half etching and the like. Theformation of the depressions facilitates the formation of openingsdescribed below in the metal plate 320. However, the present embodimentis not limited to such a mode, and the metal plate 320 which does notcontain the depressions and has a flat surface as a whole may beemployed.

Next, as shown in FIG. 3C, the openings are formed in the metal plate320 with etching or the like to expose the insulating film 310, and afirst layer 325 is formed simultaneously. When the metal plate 320 hasthe depressions, the openings can be readily constructed at thepositions corresponding to the depressions by conducting the etching inthe regions overlapping with the depressions (from a side opposite tothe depressions).

Next, as indicated by the arrow in FIG. 3C, the depressions 312 areformed at a surface of the insulating film 310 by applying physicalforce or performing etching and the like on the exposed insulating film310 (FIG. 3D). The depressions 312 may be formed by laser irradiation.The formation of such depressions 312 facilitates the formation of viasin the insulating film 310.

Next, as shown in FIG. 4A, the vias 315 are formed by applying a methodsuch as an etching method, laser irradiation, or the like on theinsulating film 310 in which the depressions 312 are formed. By thisprocess, a surface of the first wiring 300 is exposed.

Next, as shown in FIG. 4B, a second layer 330 is formed with anelectroplating method and the like. As the electroplating method, themethod described in the First Embodiment may be employed. The wiringhaving the structure in which the first layer 325 and the second layer330 are stacked is a second wiring 340.

At this time, the second layer 330 is formed so as to cover the firstlayer 325 and fill the vias 315. In other words, a thickness of thesecond layer 330 in a region overlapping with the first layer 325 isdifferent from a thickness of the second layer 330 in the vias 315, andthe latter is larger. Note that, when the thickness of the second layer330 formed in the vias 315 is small, the vias 315 may be filled with aconductive paste and the like after or before the formation of thesecond layer 330, for example. After that, a circuit wiring may beformed by processing the second layer 330 with a method such as etching,if necessary.

The thickness of the second layer 330 can be smaller than a thickness ofthe first layer 325. Specifically, the thickness of the second layer 330in the region overlapping with the first layer 325 is smaller than thethickness of the first layer 325. Therefore, the formation time of thesecond layer 330 can be reduced, and the process can be shortened. Thethickness of the first layer 325 and the second layer 330 may beselected from those described in the First Embodiment.

The first layer 325 and the second layer 330 may be different inelectrical resistivity. Alternatively, they may be different in impurityconcentration. Alternatively, they may be different in density.

Note that the second layer 330 may be formed with a sputtering methodand the like in addition to an electroplating method.

As described in the First Embodiment, in the wiring structure in thepresent embodiment, a metal layer (the first layer 325 in the presentembodiment) formed with a metal plate and having a large thickness and ametal layer (the second layer 330 in the present embodiment) formed withan electroplating method and the like and having a small thickness arehybridized. Hence, a large current can be applied by using the firstlayer 325 as a main conduction route, which allows the operation of apower device. On the other hand, the second layer 330 formed with anelectroplating method and the like can be utilized in a region in whicha large current does not flow but a wiring arrangement in a high degreeof integration is required. Therefore, wiring patterning for a controlIC is feasible. With this structure, devices such as a power device anda control IC, which require different design rules, can be arranged inthe same layer and can be connected in the same wiring process.

Fourth Embodiment

In the present embodiment, an example in which the wiring substratehaving the wiring structure described in the First Embodiment is appliedto a semiconductor package is described by using FIG. 5A to FIG. 7C.Description of the structures which are the same as those of the FirstEmbodiment may be omitted.

As shown in FIG. 6C and FIG. 7C, the wiring substrate of the presentembodiment possesses a wiring at least over or under a semiconductordevice such as a power device. Additionally, the wiring has a structurein which a layer with a large thickness and a layer with a smallthickness are hybridized. The former can be used as a flow route of alarge current, whereas the latter can be used in order to form a wiringhaving a high degree of integration.

A manufacturing method of the semiconductor package of the presentembodiment is shown in FIG. 5A to FIG. 7C. First, the semiconductordevice 420 such as a power device is bonded over a first wiring 400 witha bonding layer 410 interposed therebetween. A first terminal 422 and asecond terminal 424 are arranged as an extraction wiring under and overthe semiconductor device 420. The first wiring 400 may be a wiringmounted on an insulating substrate, a wiring formed in a layered form,or a wiring for connecting this wiring. Alternatively, the first wiring400 may be an extraction wiring or a pad formed on an IC chip or a powerdevice. An organic adhesion material such as an acrylic-based adhesivecan be used for the bonding layer 410. Alternatively, the bonding layer410 may be a metal bonding layer including a metal with a relatively lowmelting point, such as zinc and tin, or its alloy.

Next, an insulating film 430 is formed so as to cover the first wiring400 and the semiconductor device 420. As a material and a formationmethod of the insulating film 430, those described in the FirstEmbodiment may be used. The insulating film 430 protects thesemiconductor device 420 and prevents entrance of impurities such aswater and ions from outside.

Next, as shown in FIG. 5C, a metal plate 440 is bonded over theinsulating film 430. As a material and a bonding method of the metalplate 440, those shown in the First Embodiment may also be employed. Adepression may be formed at a surface which contacts with the insulatingfilm 430 by performing half etching on the metal plate 440 in advance.

Next, a first layer 445 is formed by processing the metal plate 440 withetching and the like (FIG. 6A). Here, a plurality of opening portions isformed in the metal plate 440, and the insulating film 430 is exposed.

Next, as shown in FIG. 6B, etching or laser irradiation is conducted onthe insulating film 430 over the second terminal 422 of thesemiconductor device 420, by which the region exposed in the openings isremoved and the second terminal 422 is exposed. By this process, aplurality of vias 432 is formed over the second terminal 422. Note that,before processing the insulating film 430, a depression may be formed byapplying physical force or performing laser irradiation on its surface.

After that, as shown in FIG. 6C, a second layer 450 is formed with anelectroplating method or the like so as to cover the first layer 445 andfill the vias 432. As the electroplating method, the method shown in theFirst Embodiment may be applied. The wiring having the structure inwhich the first layer 445 and the second layer 450 are stacked is asecond wiring 460. The features regarding the thickness of the firstlayer 445 and the second layer 450 are the same as those in the FirstEmbodiment.

Through the aforementioned process, a wiring having a stacked structure(first layer 445 and second layer 450) can be formed over thesemiconductor device 420. A large current for driving the semiconductordevice 420 is mainly supplied through the first layer 445, whereas awiring with a high degree of integration is formed by using the secondlayer 450.

FIG. 7A to FIG. 7C show a method for additionally forming a wiringhaving a stacked structure under the semiconductor device 420. FIG. 7Ashows a step in which the stacked wiring (second wiring 460) is formedon a top side of the semiconductor device 420. First, the first terminal422 is exposed by forming vias 434 in the first wiring 400 and thebonding layer 410 with etching or the like (FIG. 7B). Here, a pluralityof vias 434 is formed. By this process, a third layer 470 is formed. Theformation of the vias 434 may be carried out in one step bysimultaneously processing the first wiring 400 and the bonding layer410. Alternatively, openings may be initially formed in the first wiring400 with etching or the like, and then the vias 434 may be formed byprocessing the bonding layer 410 under different conditions or with adifferent method in the next step.

After that, a fourth layer 480 is formed with an electroplating methodand the like so as to cover the third layer 470 and fill the vias 434.The wiring having the structure in which the third layer 470 and thefourth layer 480 are stacked is a third wiring 490. The featuresregarding the thickness of the first wiring 400 and the fourth layer 480are the same as those of the First Embodiment.

Through the aforementioned process, a wiring having a stacked structure(third layer 470 and fourth layer 480) can be formed under thesemiconductor device 420. A large current for driving the semiconductordevice 420 is mainly supplied through the third layer 470, whereas awiring with a high degree of integration is formed by using the fourthlayer 480. The use of the manufacturing method of the present embodimentallows the production of a semiconductor package in which a wiring for alarge current and a wiring for a small current coexist in the samelayer.

Fifth Embodiment

In the present embodiment, an example in which the wiring substratehaving the wiring structures described in the First and SecondEmbodiments is applied to a semiconductor package is described by usingFIG. 8A to FIG. 10B. Note that description of the structures which arethe same as those of the First and Second Embodiments may be omitted.

As shown in FIG. 9B and FIG. 10B, the wiring substrate of the presentembodiment possesses a wiring at least over or under a semiconductordevice such as a power device. Additionally, the wiring has a structurein which a layer with a large thickness and a layer with a smallthickness are hybridized. The former can be used as a flow route of alarge current, whereas the latter can be used in order to form a wiringhaving a high degree of integration.

A manufacturing method of the semiconductor package of the presentembodiment is shown in FIG. 8A to FIG. 10B. First, a semiconductordevice 520 such as a power device is bonded over a first wiring 500 witha bonding layer 510 interposed therebetween (FIG. 8A). A first terminal522 and a second terminal 524 are arranged as an extraction wiring underand over the semiconductor device 520. The first wiring 500 may be awiring mounted on an insulating substrate, a wiring formed in a layeredform, or a wiring for connecting this wiring. Alternatively, the firstwiring 500 may be an extraction wiring or a pad formed on an IC chip ora power device. An organic adhesion material such as an acrylic-basedadhesive can be used for the bonding layer 510. Alternatively, thebonding layer 510 may be a metal bonding layer including a metal with arelatively low melting point, such as zinc and tin, or its alloy.

Next, an insulating film 530 is formed so as to cover the first wiring500 and the semiconductor device 520 (FIG. 8B). As a material and aformation method of the insulating film 530, those described in theFirst Embodiment may be used. The insulating film 530 protects thesemiconductor device 520 and prevents entrance of impurities such aswater and ions from outside.

Next, as shown in FIG. 8C, vias 532 are formed in the insulating film530 to expose the second terminal 524. Here, a plurality of vias 532 isformed. The formation of the vias 532 can be carried out with etching,laser irradiation, or the like.

After that, a second layer 540 is formed over the insulating film 530 soas to fill the vias 532 with an electroplating method, a sputteringmethod, or the like described in the First Embodiment (FIG. 9A).

Next, as shown in FIG. 9B, a metal plate is bonded over the second layer540 with a metal bonding layer 550 interposed therebetween to form afirst layer 560. As the metal plate and the metal bonding layer 550,those shown in the Second Embodiment may be used, and the bonding may beperformed with the same method as that of the Second Embodiment. Thefeatures regarding the first layer 560 and the second layer 540 are thesame as that of the Second Embodiment. After that, the first layer 560may be processed into a required shape by using an etching method andthe like. The wiring having the structure in which the first layer 560and the second layer 540 are stacked is a second wiring 570.

Through the aforementioned process, a wiring having a stacked structure(first layer 560 and second layer 540) can be formed over thesemiconductor device 520. A large current for driving the semiconductordevice 520 is mainly supplied through the first layer 560, whereas awiring with a high integration degree is formed by using the secondlayer 540.

FIG. 10A and FIG. 10B show a method for additionally forming a wiringhaving the stacked structure shown in the First Embodiment under thesemiconductor device 520. First, the first terminal 522 is exposed byforming vias 534 in the first wiring 500 and the bonding layer 510 withetching or the like (FIG. 10A). Here, a plurality of vias 534 is formed.By this process, a third layer 580 is formed. The formation of the vias534 may be carried out in one step by simultaneously processing thefirst wiring 500 and the bonding layer 510. Alternatively, openings maybe initially formed in the first wiring 500 with etching or the like,and then the vias 534 may be formed by processing the bonding layer 510under different conditions or with a different method in the next step.

After that, a fourth layer 585 is formed with an electroplating methodand the like so as to cover the third layer 580 and fill the vias 534.The wiring having the structure in which the third layer 580 and thefourth layer 585 are stacked is a third wiring 590. The featuresregarding the thickness of the third layer 580 and the fourth layer 585are the same as those in the First Embodiment. After that, the fourthlayer 585 may be processed to form a circuit wiring having a high degreeof integration, for example.

Through the aforementioned process, a wiring having a stacked structure(third layer 580 and fourth layer 585) can be formed under thesemiconductor device 520. A large current for driving the semiconductordevice 520 is mainly supplied through the third layer 580, whereas awiring with a high degree of integration is formed by using the fourthlayer 585. The use of the manufacturing method of the present embodimentallows the production of a semiconductor package in which a wiring for alarge current and a wiring for a small current coexist in the samelayer.

Sixth Embodiment

In the present embodiment, a semiconductor package in which a wiring fora large current and a wiring for a small current coexist in the samelayer and in which a semiconductor device driven with small electricpower and a power device applied with a large current coexist in thesame layer is explained by using FIG. 11 and FIG. 12.

FIG. 11 is a circuit diagram of the semiconductor package shown in thepresent embodiment. Reference numeral 600 is a control IC which controlstwo power devices 610 and 620. The power devices 610 and 620 have astructure of a transistor, and drains thereof are electrically connectedto each other. The control IC 600 is a device driven with a relativelysmall current, while the power devices 610 and 620 are each a devicedriven with a large current. Therefore, a wiring connected to thecontrol IC 600 is preferred to be a wiring with a small thickness,whereas a wiring with a large thickness is connected to the powerdevices 610 and 620.

FIG. 12 is an example of a cross-sectional structure of the wiringsubstrate shown in FIG. 11. The wiring substrate of the presentembodiment has first wirings 630, 632, and 634. The control IC 600 isfixed over the first wiring 630 with a bonding layer 640 interposedtherebetween. As the bonding layer 640, that shown in the FourthEmbodiment can be used.

A first terminal 612 and a second terminal 614 are provided to the powerdevice 610, and a first terminal 622 and a second terminal 624 areprovided to the power device 620 similarly. The power device 610 isfixed over the first wiring 632 by using, for example, a metal bondinglayer 650 and electrically connected to the first wiring 632. Similarly,the power device 620 is fixed over the first wiring 634 by using, forexample, a metal bonding layer 650 and electrically connected to thefirst wiring 634.

An insulating film 660 is formed so as to embed the control IC 600 andthe power devices 610 and 620, and the insulating film 660 coversterminals 602 of the control IC 600 and the second terminals 614 and 624of the power devices 610 and 620. The insulating film 660 can have thestructure which is the same as that of the insulating film 110 of theFirst Embodiment.

A first layer 670 having a large thickness is arranged over the powerdevices 610 and 620 with the insulating film 660 interposedtherebetween. The first layer 670 can have the structure which is thesame as that of the first layer 125 of the First Embodiment and can beformed with the method which is the same as that of the first layer 125of the First embodiment. This first layer 670 functions as a main wiringroute for supplying a large current to the power devices 610 and 620.

Vias are formed in the first layer 670 and the insulating film 660 toexpose the terminals 602 of the control IC 602, the second terminals 614and 624 of the power devices 610 and 620, and the first wirings 632 and634, and a second layer 680 is formed over the first layer 670 with anelectroplating method and the like to fill the vias. The second layer680 can have the structure which is the same as that of the second layer130 of the First Embodiment and can be formed with the method which isthe same as that of the second layer 130 of the First Embodiment. Notethat, the second layer 680 is further subjected to patterning in FIG. 12and utilized to supply signals from the control IC, for example. Thewiring in which the first layer 670 and the second layer 680 are stackedis a second wiring 690.

An upper wiring 695 is further stacked over the second layer 680 with aninsulating film 665 interposed therebetween. This upper wiring 695 canbe formed with the method which is the same as that of the second layer680.

As described above, the semiconductor package of the present embodimenthas a structure in which a wiring for a large current (first layer 670)and a wiring for a small current (second layer 680) coexist in the samelayer. With this structure, devices such as a power device and a controlIC, which require different design rules, can be arranged in the samelayer and connected to each other in the same wiring process.

Seventh Embodiment

In the present embodiment, a semiconductor package in which a wiring fora large current and a wiring for a small current coexist in the samelayer and in which a semiconductor device driven with small electricpower and a power device applied with a large current coexist in thesame layer is explained by using FIG. 11 and FIG. 13. Note that thepresent embodiment is different from the Sixth Embodiment in structureof the second wiring. The structures which are different from those ofthe Sixth Embodiment are mainly explained and an explanation of the samestructures may be omitted.

FIG. 11 is a circuit diagram of the semiconductor package shown in thepresent embodiment and the same as that of the Sixth Embodiment. FIG. 13is an example of a cross-sectional structure of the wiring substrateshown in FIG. 11. In the insulating film 660 are formed vias which reachthe terminals 602 of the control IC, the second terminal 614 of thepower device 610, the second terminal 624 of the power device 620, andthe first wirings 632 and 634, and a second layer 700 is formed so as tofill these vias. The second layer 700 can be formed by using thematerial and the method which are the same as those of the second layer220 of the Second Embodiment.

A first layer 720 having a large thickness is disposed over a region ofthe second layer 700, which overlaps with the power devices 610 and 620,with a metal bonding layer 710 interposed therebetween. The first layer720 can have the same structure as that of the first layer 125 of theFirst Embodiment and can be formed with the method which is the same asthat of the first layer 125 of the First Embodiment. The stack of thefirst layer 720 and the second layer 700 is a second wiring 730 andcorresponds to the second wiring 240 of the Second Embodiment. The firstlayer 720 functions as a main wiring route for supplying a large currentto the power devices 610 and 620, whereas the second layer 700 is usedfor fabricating a wiring with a high degree of integration and forsupplying signals from the control IC, for example.

An upper wiring 750 is further stacked over the first layer 720 with theinsulating film 740 interposed therebetween. This upper wiring 750 canbe formed with the method which is the same as that of the second layer700.

As described above, the wiring substrate of the present embodiment has astructure in which a wiring for a large current (first layer 720) and awiring for a small current (second layer 700) coexist in the same layer.With this structure, devices such as a power device and a control IC,which require different design rules, can be arranged in the same layerand connected to each other in the same wiring process.

What is claimed is:
 1. A wiring substrate comprising: a first wiring; aninsulating film over the first wiring, the insulating film comprising avia; and a second wiring over the insulating film, wherein the secondwiring has a stacked structure including: a first layer; and a secondlayer covering the first layer, wherein the second layer is in directcontact with the first wiring in the via, and wherein a thickness of thesecond layer in a region overlapping with the first layer is differentfrom a thickness of the second layer in the via.
 2. The wiring substrateaccording to claim 1, wherein the thickness of the second layer in thevia is larger than the thickness of the second layer in the regionoverlapping with the first layer.
 3. The wiring substrate according toclaim 1, wherein a thickness of the first layer is larger than thethickness of the second layer in the region overlapping with the firstlayer.
 4. The wiring substrate according to claim 1, wherein a topsurface of the insulating film has a depression between the via and thefirst layer.
 5. A wiring substrate comprising: a first wiring; aninsulating film over the first wiring, the insulating film comprising avia; and a second wiring over the insulating film, wherein the secondwiring has a stacked structure including: a second layer in directcontact with the first wiring in the via; and a first layer over andelectrically connected to the second layer, and wherein a thickness ofthe second layer in a region overlapping with the insulating film isdifferent from a thickness of the first layer in the via.
 6. The wiringsubstrate according to claim 5, wherein a thickness of the second layerin the via is larger than the thickness of the second layer in theregion overlapping with the insulating film.
 7. The wiring substrateaccording to claim 5, wherein the thickness of the first layer is largerthan the thickness of the second layer in the region overlapping withthe insulating film.
 8. A semiconductor package comprising: asemiconductor device comprising a terminal; an insulating film over theterminal, the insulating film comprising a via; and a wiring over theinsulating film, wherein the wiring has a stacked structure including: afirst layer; and a second layer covering the first layer; wherein thesecond layer is in direct contact with the terminal in the via, andwherein a thickness of the second layer in a region overlapping with thefirst layer is different from a thickness of the second layer in thevia.
 9. The semiconductor package according to claim 8, wherein thethickness of the second layer in the via is larger than the thickness ofthe second layer in the region overlapping with the first layer.
 10. Thesemiconductor package according to claim 8, wherein a thickness of thefirst layer is larger than the thickness of the second layer in theregion overlapping with the first layer.
 11. The semiconductor packageaccording to claim 8, wherein a top surface of the insulating film has adepression between the via and the first layer.
 12. A semiconductorpackage comprising: a semiconductor device comprising a terminal; aninsulating film over the terminal, the insulating film comprising a via;and a wiring over the insulating film, wherein the wiring has a stackedstructure including: a second layer in direct contact with the terminalin the via; and a first layer over and electrically connected to thesecond layer, and wherein a thickness of the second layer in a regionoverlapping with the insulating film is different from a thickness ofthe second layer in the via.
 13. The semiconductor package according toclaim 12, wherein the thickness of the second layer in the via is largerthan the thickness of the second layer in the region overlapping withthe insulating film.
 14. The semiconductor package according to claim12, wherein a thickness of the first layer is larger than the thicknessof the second layer in the region overlapping with the insulating film.15. A manufacturing method of a wiring substrate, the manufacturingmethod including: forming an insulating film over a first wiring; andforming a second wiring over the insulating film, the second wiringcomprising a first layer and a second layer, wherein the formation ofthe second wiring includes: forming the second layer by bonding a metalplate to the insulating film; exposing the insulating film by forming anopening portion in the second layer; exposing the first wiring byforming a via in the insulating film; and forming the first layer withan electroplating method so that the first layer is located over and indirect contact with the first wiring and the second layer.
 16. Themanufacturing method of a wiring substrate according to claim 15,wherein a thickness of the second layer in the via is larger than athickness of the second layer in a region overlapping with the firstlayer.
 17. The manufacturing method of a wiring substrate according toclaim 15, wherein a thickness of the first layer is larger than athickness of the second layer in a region overlapping with the firstlayer.
 18. A manufacturing method of a wiring substrate, themanufacturing method including: forming an insulating film over a firstwiring; exposing the first wiring by forming a via in the insulatingfilm; and forming a second wiring over the insulating film, the secondwiring comprising a first layer and a second layer, wherein theformation of the second wiring includes: forming the second layer withan electroplating method so that the second layer is located over and incontact with the first wiring and the insulating film; and forming thefirst layer by disposing a metal plate over the second layer so that thefirst layer is electrically connected to the second layer.
 19. Themanufacturing method of a wiring substrate according to claim 18,wherein a thickness of the second layer in the via is larger than athickness of the second layer in a region overlapping with theinsulating film.
 20. The manufacturing method of a wiring substrateaccording to claim 18, wherein a thickness of the first layer is largerthan a thickness of the second layer in a region overlapping with theinsulating film.
 21. A manufacturing method of a semiconductor package,the manufacturing method comprising: forming a semiconductor device overa first wiring, the semiconductor device comprising a first terminal anda second terminal; forming an insulating film over the second terminal;and forming a second wiring over the insulating film, the second wiringincluding a first layer and a second layer, wherein the formation of thesecond wiring includes: forming the second layer by bonding a metalplate to the insulating film; exposing the insulating film by forming anopening portion in the second layer; exposing the first wiring byforming a via in the insulating film; and forming the first layer withan electroplating method so that the first layer is located over and indirect contact with the first wiring and the second layer.
 22. Themanufacturing method of a semiconductor package according to claim 21,wherein a thickness of the second layer in the via is larger than athickness of the second layer in a region overlapping with the firstlayer.
 23. The manufacturing method of a semiconductor package accordingto claim 22, wherein a thickness of the first layer is larger than athickness of the second layer in the region overlapping with the firstlayer.
 24. The manufacturing method of a semiconductor package accordingto claim 22, wherein a top surface of the insulating film has adepression between the via and the first layer.
 25. A manufacturingmethod of a semiconductor package, the manufacturing method comprising:forming a semiconductor device over the first wiring, the semiconductordevice comprising a first terminal and a second terminal; forming aninsulating film over the second terminal; and forming a second wiringover the insulating film, the second wiring including a first layer anda second layer, wherein the formation of the second wiring comprises:forming the second layer with an electroplating method so that thesecond layer is located over and in contact with the first wiring andthe insulating film; and forming the first layer by disposing a metalplate over the second layer so that the first layer is electricallyconnected to the second layer.
 26. The manufacturing method of a wiringsubstrate according to claim 25, wherein a thickness of the second layerin the via is larger than a thickness of the second layer in a regionoverlapping with the insulating film.
 27. The manufacturing method of awiring substrate according to claim 25, wherein a thickness of the firstlayer is larger than a thickness of the second layer in a regionoverlapping with the insulating film.